Claude Mythos Preview vs Mistral Medium 3 Instruct
Claude Mythos Preview (2026) and Mistral Medium 3 Instruct (2025) are frontier reasoning models from Anthropic and MistralAI. Claude Mythos Preview ships a 1M-token context window, while Mistral Medium 3 Instruct ships a 128K-token context window. On pricing, Mistral Medium 3 Instruct costs $0.4/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Mistral Medium 3 Instruct is ~6150% cheaper at $0.4/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos Preview | Mistral Medium 3 Instruct |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 1M | 128K |
| Cheapest output | $125/1M tokens | $2/1M tokens |
| Provider routes | 2 tracked | 2 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Claude Mythos Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos Preview uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- Mistral Medium 3 Instruct has the lower cheapest tracked output price at $2/1M tokens.
- Local decision data tags Mistral Medium 3 Instruct for Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Mythos Preview
$51,250
Cheapest tracked route: Anthropic
Mistral Medium 3 Instruct
$820
Cheapest tracked route: Mistral AI Studio
Estimated monthly gap: $50,430. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos Preview and Mistral Medium 3 Instruct; plan for SDK, billing, or endpoint changes.
- Mistral Medium 3 Instruct is $123/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- No overlapping tracked provider route is sourced for Mistral Medium 3 Instruct and Claude Mythos Preview; plan for SDK, billing, or endpoint changes.
- Claude Mythos Preview is $123/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2025-10-01 |
| Context window | 1M | 128K |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | 1 |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | Mistral Medium 3 Instruct |
|---|---|---|
| Input price | $25/1M tokens | $0.4/1M tokens |
| Output price | $125/1M tokens | $2/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | Mistral Medium 3 Instruct |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Claude Mythos Preview, multimodal input: Claude Mythos Preview, reasoning mode: Claude Mythos Preview, function calling: Claude Mythos Preview, tool use: Claude Mythos Preview, structured outputs: Claude Mythos Preview, and code execution: Claude Mythos Preview. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Mythos Preview lists $25/1M input and $125/1M output tokens, while Mistral Medium 3 Instruct lists $0.4/1M input and $2/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Medium 3 Instruct lower by about $54.12 per million blended tokens. Availability is 2 providers versus 2, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support and larger context windows are central to the workload. Choose Mistral Medium 3 Instruct when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Mythos Preview or Mistral Medium 3 Instruct?
Claude Mythos Preview supports 1M tokens, while Mistral Medium 3 Instruct supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Mythos Preview or Mistral Medium 3 Instruct?
Mistral Medium 3 Instruct is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. Mistral Medium 3 Instruct costs $0.4/1M input and $2/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or Mistral Medium 3 Instruct open source?
Claude Mythos Preview is listed under Proprietary. Mistral Medium 3 Instruct is listed under 1. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Mythos Preview or Mistral Medium 3 Instruct?
Claude Mythos Preview has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Mythos Preview or Mistral Medium 3 Instruct?
Claude Mythos Preview has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Mythos Preview and Mistral Medium 3 Instruct?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. Mistral Medium 3 Instruct is available on NVIDIA NIM and Mistral AI Studio. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.